Re: [Qemu-devel] [PATCH V5 6/6] coroutine: reduce stack size to 64kB

From: Eric Blake <eblake@redhat.com>
To: Peter Lieven <pl@kamp.de>, qemu-devel@nongnu.org
Cc: kwolf@redhat.com, mreitz@redhat.com, pbonzini@redhat.com,
	mst@redhat.com, dgilbert@redhat.com, peter.maydell@linaro.org,
	rth@twiddle.net, armbru@redhat.com
Subject: Re: [Qemu-devel] [PATCH V5 6/6] coroutine: reduce stack size to 64kB
Date: Tue, 12 Jul 2016 11:39:24 -0600	[thread overview]
Message-ID: <57852B4C.6050104@redhat.com> (raw)
In-Reply-To: <1468340586-19304-7-git-send-email-pl@kamp.de>

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On 07/12/2016 10:23 AM, Peter Lieven wrote:
> evaluation with the recently introduced maximum stack usage monitoring revealed
> that the actual used stack size was never above 4kB so allocating 1MB stack
> for each coroutine is a lot of wasted memory. So reduce the stack size to
> 64kB which should still give enough head room. The guard page added
> in qemu_alloc_stack will catch a potential stack overflow introduced
> by this commit.
> 
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  include/qemu/coroutine_int.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Eric Blake <eblake@redhat.com>

> 
> diff --git a/include/qemu/coroutine_int.h b/include/qemu/coroutine_int.h
> index eac323a..f84d777 100644
> --- a/include/qemu/coroutine_int.h
> +++ b/include/qemu/coroutine_int.h
> @@ -28,7 +28,7 @@
>  #include "qemu/queue.h"
>  #include "qemu/coroutine.h"
>  
> -#define COROUTINE_STACK_SIZE (1 << 20)
> +#define COROUTINE_STACK_SIZE (1 << 16)
>  
>  typedef enum {
>      COROUTINE_YIELD = 1,
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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